1. Field of the Invention
The object of the present invention is an apparatus, wherein defect points in veneer sheets coming from a dryer are patched. Prior to this processing step, the sheets have been sorted in terms of defect points so that a defect point to be patched is below a certain size.
2. Description of the Related Art
Traditionally, defect points have been patched by hand, by pressing the defect veneer point out form the sheet with a punch, and by forcing an intact veneer patch to the hole made by the punch, fitting with a tight clearance to the hole.
The patching function has also been mechanized, where the first step has been the mechanization of the punching operation and the insertion of the patch. The veneer sheet being handled has been moved by hand in to position with a patching unit, called a patching head, for carrying out the patching operation.
In further development of the mechanization, machine vision devices have been introduced, by means of which it has been possible to observe the veneer sheet's whole area for detecting defect points requiring patching. Veneer-specific information given by such a detection device has been fed to a control device, which in turn has controlled a device moving the veneer for allocating defect points in position with a patching unit. The patching spot is aligned by conveying the veneer in length-width directions, so that when the patching area approaches the midpoint of veneer's advancement, the holding function of the conveying device is moved over the patching apparatus to an area of the veneer having passed patching.